Fuel regulating valve



May 2.7, 1969 N. E. SWEDBQG 3,446,230

FUEL REGULATING .VALVE Filed June 13, 1966 United States Patent 3,446,230 FUEL REGULATING VALVE Nils E. Swedberg, Rockford, Ill., assignor to Sundstrand Corporation, a corporation of Delaware Filed June 13, 1966, Ser. No. 557,056

Int. Cl. F16k 11/22; F02m 55/00 US. Cl. 137--108 18 Claims ABSTRACT OF THE DISCLOSURE A fuel burner regulating valve including a main valve for regulating the supply of fuel to a burner nozzle and a flow responsive valve upstream and in series with the main valve for bypassing fluid from the main valve until a predetermined flow rate is achieved.

This invention relates generally to fuel pumps and more particularly to a regulating valve adapted for use in connection with oil burner pumps.

Oil burner units have in the past been provided with regulating valves between the oil burner nozzles which discharge fuel into the combustion chamber and the fuel pump which supplies fuel oil to the nozzles. Generally, these regulating valves Open upon delivery a predetermined supply pressure from the pump, regulate constant pressure flow to the burner nozzles, and close to shut off the supply of fuel oil to the nozzles when the pump is turned off on shut-down. In addition to regulating the pressure of fuel oil delivered to the burner nozzles, these valves oftentimes have a bypass function of diverting a large portion of the fuel oil delivered by the pump back to the pump or reservoir instead of delivering it to the burner nozzles so that only a portion of the fuel Oil supplied by the pump is delivered to the nozzles.

One of the basic problems in fuel oil regulating valves of this general character is that the transient variations in the fuel oil discharge from the nozzles both at startup and at shut-down cause highly undesirable smoking in the combustion chamber at these times. Various means have been provided in the past in attempts to effect rapid valve action and minimize the problem of smoking, but to a large extent the prior solutions have not solved all of the problems of a valve for this purpose, and have had certain characteristics that detract from the performance of the regulating valve.

It is, therefore, a primary object of the present invention to provide a new and improved regulating Valve assembly for a fuel oil burner.

It is another object of the present invention to provide a regulating valve assembly of the type described which opens to port fluid to the oil burner nozzles only after the pump has reached a high rpm. and the fuel oil pressure is at a 'high level thereby reducing or even eliminating smoking in the combustion chamber at startup.

Another object of the present invention is to provide a new and improved regulating valve assembly of the type described which closes at a high pump rpm. and high fuel oil pressure to quickly cut off the supply of oil to the nozzles at shut-down to reduce or even eliminate smoking in the combustion chamber at this time.

It is still another object of the present invention to provide a new and improved regulating valve of the type described which permits fast purging of the pump without returning any of the air entrained fuel to the pumpor reservoir at this time.

A further object of the present invention is to provide a new and improved regulating valve assembly of the type described which maintains a low pressure head against the pump during starting to reduce the required motor starting torque, and which does not reduce the pumps capability of high lift or high vacuum. The present regulating valve has a predetermined delay time prior to porting fuel to the burner nozzles during which times a low pressure condition exists enabling a lower pump starting torque. Furthermore, because of the lack of a necessity for any high pressure bleed slots in the present regulating valve, high vacuum and high nozzle capacities are maintained.

It is a still further object of the present invention to provide a new and improved regulating valve of the type described of a simplified and compact construction, adjustable, and which maintains a constant pressure flow to the burner nozzles from the instant the valve opens to the instant it closes.

Other objects and advantages will be readily apparent from the following detailed description taken in connection with the accompanying drawing which is 21 diagrammatic view of a fuel circuit for an oil burner including a regulating valve assembly in accordance with the present invention. 1

While an illustrative embodiment of the invention is shown in the drawing and will be described in detail herein, the invention is susceptible of embodiment in many different forms and it should be understood that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the inventon to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

In the drawing an internal gear pump 10, of the crescent type, is provided for drawing fuel oil from a reservoir 11 and delivering it under pressure to a regulating valve assembly 12 which serve to regulate the flow of fuel to fuel burner nozzles (not shown) through a burner nozzle outlet port 14. The valve 12 also serves to bypass a portion of the fuel from the pump 10 back to the reservoir through a return passage 15.

The pump 10, the reservoir 11 and the regulating valve 12, in addition to the associated passages, are housed or formed within a single housing assembly 16, although they are shown separately in the drawing for clarity. The pump 10 is driven by a suitable motor (not shown) through a pump shaft 17 adapted to be connected to a driving electric motor. A suitable shaft seal assembly 20 is provided around the shaft where it projects from the casing or housing assembly 16. Further, a suitable filter 22 is provided in the reservoir 11 for filtering fluid entering the reservoir through the bypass or retrun passage 15 or through a make-up port 23 which may be used to supply additional fluid to the reservoir as needed.

An air purging valve 25 is provided threaded in the housing 16 for purging fuel (with air entrained) supplied from the pump 10 to the regulating valve 12 after initial installation or extended shut-down. Valve 25 is described in more detail in the copending application of Raymond W. Roper, Ser. No. 453,558, filed Apr. 28, 1965, assigned to the assignee of the present invention, and reference should be made thereto for a more complete description of the function and operation of the valve 25. In brief, a conical seating surface 26 on the end of valve 25 engages a complementary seat in the housing 16 preventing the escape of fluid through passage 27 which continually communicates with the outlet of the pump 10. When opened, however, by unthreading the valve 25, fluid is permitted to pass through passage 27 around a reduced portion 28 on the valve through passages 29 and 30 and out into a suitable receptacle adjacent the unit.

The regulating valve assembly 12 is provided for the purpose of regulating the flow of fuel from the pump 10 through the burner nozzle outlet 14, as described above.

3 It includes a cylindrical valve bore 40 in housing 16 with a burner nozzle outlet fitting 41 threaded in one end thereof having a central projection 42 extending within the bore and defining a stationary valve seat on the end thereof.

An outlet passage 44, formed in the housing 16, connects the outlet of the pump with a central portion of the valve bore 40. The return passage communicates with one end of the bore for conveying fluid therein back to the reservoir 11. Leakage from around the shaft seal assembly along the shaft is also returned to the reservoir through a passage 45 which communicates with valve bore at the same end as the return passage 15.

Slidable in the bore 40 is a main regulating hollow spool valve member 50 having spaced annular lands 51, 52 and 53 thereon. The upper end of the hollow valve member 50 is closed by a back-up washer 52' contiguous with a resilient washer 53 both retained within the end of the spool member by retaining collar 54. The resilient Washer 53 engages the valves set on the outlet projection 42 and prevents flow, in the position shown, from a chamber 56 (defined by the valve member 50 in the valve bore) through the outlet port 14.

A coil compression spring 60 is provided for biasing the valve member 50 toward its closed position where washer 53 engages the stationary outlet seat 42. The lower end of coil spring 60 reacts against a nonrotatable abutment 61 threadedly carried by an adjustable screw 63 threaded in a fitting 64 which is in turn threaded in the housing 16. A suitable cap 65, provided for the fitting t 64, may be removed so that the screw 63 may be rotated to adjust the compressive force of the spring 60 on the valve member 50 to thus vary the regulated pressure of fuel oil through the outlet port 14. The other end of the compression spring 60 reacts against a spring seat 70 fixed within the lower end of valve member 50.

When sufficient fluid pressure occurs in chamber 56, acting on the upper end of valve member 50, the valve will move downwardly against the force of spring 60 permitting fuel to flow out the outlet port 14 to the burner nozzles. Spring 60 will then regulate a constant pressure flow in the outlet port 14. The land 51 is positioned so that after the valve member 50 moves downwardly to its regulating position, the upper end of the land will be below annular channel 72 permitting excess fuel oil to be bypassed through a bypass passage 77 communicating with the lower end of the bore 40 and the return passage 15 so that a portion of the fuel bypasses and returns to the reservoir 11.

In accordance with the present invention, another hollow valve member 75 is provided slidable within the valve member 50 for controlling the flow of fuel from supply passage 44 to the valve chamber 56 and for controlling flow through vent ports 76 in valve member 50 between lands 51 and 52. These vent ports communicate with the bypass passage 77.

The valve member 75 has a frustoconical surface 80 on one end thereof with a flat valve seat 81 engageable with a complementary flat valve seat 82 formed on the inner end of the spring seat 70. The spring seat 70 also has a frustoconical surface 83 defining with the surface 80 an annular chamber 86 formed within the valve member 50 in continuous communication with the supply passage 44 through ports 87 extending through valve member 50 betweenlands 52 and 53.

An orifice 89 extends centrally through the valve member 75 and is adapted when the valve member is open to convey fluid from chamber 86 into the hollow interiors of valve members 75 and 50. Valve member 75 is biased to its closed position shown by a coil compression spring 90 mounted at one end in a spring seat 92 fixed within valve member 50, and reacting at its other end against surface 93 within the valve member 75 pushing it downwardly against the spring seat 70. An upper portion 95 of the valve member 75 closes the vents 76 as the valve member opens preventing the flow of fuel from the interior of the valve members and the valve chamber 56 out the vents to thereby subject the upper end of the valve member to full supply pressure through ports 96 in the upper end of the valve member 50.

The valve member 75 is a differential flow responsive valve, with supply fluid pressure acting on surfaces and 81 urging the valve member 75 upwardly toward its open position, and supply fluid at a pressure determined by the drop across orifice 89 acting on the inner surfaces 93 and 93' urging the valve member 75 downwardly to its closed position with the spring 90. Therefore, there is a net hydraulic force acting on the valve member 75 in a direction with the flow through the orifice 89 depending upon the pressure drop across the orifice. If one satisfactory valve construction for use with a fuel pump having an operating speed range and flow of approximately 3200 rpm. and 16 gallons per hour, respectively, the orifice 89 was 0.046 inch in diameter and 0.094 inch in length. The spring opposes this net hydraulic force acting on valve member 75 and will compress to a length where an equilibrium is attained between the spring force and the net hydraulic force acting on the differential valve 75. Hence, the travel of the valve 75 Will be in proportion to the flow through the orifice 89.

At the lower flows, the fluid flow from the orifice 89 will flow through the vent ports 76 and out the bypass passage 77 back to the reservoir 11. This lowers the starting torque requirements on the pump 10. The orifice 89 is sized so that valve member 75 requires a high rate of flow and high pump r.p.m. before it closes vents 76, and until vents 76 are closed, the pressure in the valve chamber 56 is at a low value.

Turning now to the operation of the present device, when the pump 10 is initially starting after installation or extended shut-down, the purging plug 25 is unseated permitting the fuel and air mixture to flow through passage 27 and out through the central bore 30 of the purging valve. At this time, the spring 90 is of sufiicient strength compared with the low hydraulic force of fluid on surface '80 to maintain the valve member 75 closed so that air and oil may not enter the orifice 89 and are blocked from entering either the valve chamber 56 or the return line 77 On most starts purging is unnecessary and the valve 25 is seated. The discharge from the pump through passage 44 is in proportion to the speed of rotation of shaft 17. The supply fluid from the pump enters chamber 86 and as pressure builds up to a predetermined value, the valve member 75 will open permitting supply flow through orifice 89. As the flow through orifice 89 increases, the valve member 75 will move upwardly and close the vents 76 at a predetermined flow, and until this time the valve chamber 56 is at low return pressure. When the vents are closed, the pressure within the valve members 75 and 50, as well as in the valve chamber 56, rapidly increases and the force of the fluid acting on the upper end of valve member 50 opposing the main spring 60, rapidly reaches a magnitude where it overcomes the main spring force. The valve member 50 will then move downwardly lifting the valve Washer 53' from the outlet nozzle seat and permitting fuel flow through the nozzle outlet 14 to the burner nozzles. The limited delay time from the pump start-up until a sufficient pressure occurs in chamber 56 to open the main valve member 50, lowers the starting torque requirement on the pump and results in a high fuel oil pressure and high pump rpm. at the time the valve member 50 opens to eliminate or reduce smoking at start-up.

With the valve member 50' open,-the spring 60 serves to regulate a constant pressure flow of fuel to the burner nozzles through the port 14. During normal operation, the valve member 50 moves to a point where the upper surface of land 51 moves below the channel 72 permitting excess oil to flow into the bypass passage 77 to the reservoir through the return passage 15.

When the motor is shut oif when shut-down is desired, the flow from the pump begins to decrease causing a corresponding decrease in the pressure drop across orifice 89. This reduction in the pressure drop decreases the net hydraulic force acting on the valve member 75 causing the spring 90 to move the valve member toward its closed position. When the flow is decreased to a predetermined, but still high, value, the valve 75 will uncover the vents 76 causing the hydraulic pressure within the valve members and the valve chamber 56 to drop rapidly to a low value on the order of zero p.s.i. In actual construction, the valve land 51 is never wide enough to close off the lower edge of annular chamber 72. This upsets the balance between the force of the main spring 60 and the hydraulic force acting on the upper end of valve member 50 so that the valve member 50 will move rapidly to its closed position shown cutting off the supply of fuel to the nozzles. It is this sudden pressure loss in the valve chamber 56 and within the valve members when the vents 76 are uncovered that permits a fast cutoff of the fuel flow to the nozzles at a high pump r.p.m.

Further decrease in the supply flow causes the spring 90 to urge the valve member 75 to its fully closed position engaging the spring seat 70.

It should be understood there are no high pressure bleed slots in the present regulating valve construction so that high vacuum and high nozzle capabilities are maintained.

Furthermore, due to the rapid pressure build-up in chamber 56 after the vents 76 are closed and the sudden loss of pressure in this chamber when the vents are open, the valve 50 will maintain a constant pressure flow through the outlet nozzle 14 from the instant the valve opens to the instant it closes.

I claim:

1. A fuel burner valve device for controlling the flow of fuel between a fuel pump and a burner nozzle, comprising: passage means for supplying fluid from said pump, a regulating valve including a valve chamber having a burner nozzle outlet port therein, said passage means being connected to supply fluid to said chamber, a valve member in said chamber movable from a closed position preventing the flow of fluid from said chamber through said burner nozzle port and an open position permitting fluid flow through said nozzle port, means biasing said valve member to its closed position, and separate valve means in series between said pump and said chamber responsive to flow from said pump for preventing the flow of fluid to said chamber when the flow from the pump falls below a predetermined value.

2. A fuel burner valve device for controlling the flow of fuel between a fuel pump and a burner nozzle, comprising: passage means for supplying fluid from said pump, a regulating valve including a valve chamber having a burner nozzle outlet port therein, said passage means being connected to supply fluid to said chamber, a valve member in said chamber movable from a closed position preventing the flow of fluid from said chamber through said burner nozzle port and an open position permitting fluid flow through said nozzle port, means biasing said valve member to its closed position, and separate valve means in series between said pump and said chamber responsive to flow from said pump for venting said chamber when the flow from the pump falls below a first predetermined value and for preventing the flow of fluid to said chamber when the flow from the pump falls below a second predetermined value below said first predetermined value, whereby said valve member moves rapidly to its closed position.

3. The combination defined in claim 2, and further including bypass valve means operable upon a predetermined movement of said valve member to bypass a portion of the fluid in said supply passage means so that only a portion of the fluid passes through said outlet port when the pump is at operating speeds.

4. A fuel burner valve device for controlling the flow of fuel between a fuel pump and a burner nozzle, comprising: passage means for supplying fluid from said pump, a regulating valve including a valve chamber having a burner nozzle outlet port therein, said passage means being connected to supply fluid to said chamber, a valve member in said chamber movable from a closed position preventing the flow of fluid from said chamber through said burner nozzle port and an open position permitting fluid flow through said nozzle port, means biasing said valve member to its closed position, valve means between said pump and said chamber responsive to flow from said pump for venting said chamber when the flow from the pump falls below a first predetermined value and for preventing the flow of fluid to said chamber when the flow from the pump falls below a second predetermined value below said first predetermined value, whereby said valve member moves rapidly to its closed position, said valve means including a second valve member slidable in said first valve member, said second valve member being movable from a closed position blocking flow from said supply passage means to said valve chamber to an open position permitting flow from said supply passage means to said chamber, means biasing said second valve member to its closed position, and said second valve member being responsive to flow in said supply passage means and having an orifice therein constructed to convey fluid from the supply passage means to said chamber.

5. A fuel burner valve device for controlling the flow of fuel between a fuel pump and a burner nozzle, comprising: passage means for supplying fluid from said pump, a regulating valve including a valve chamber having a burner nozzle outlet port therein, said passage means being connected to supply fluid to said chamber, a valve member in said chamber movable from a closed position preventing the flow of fluid from said chamber through said burner nozzle port and an open position permitting fluid flow through said nozzle port, means biasing said valve member to its closed position, valve means between said pump and said chamber responsive to flow from said pump for venting said chamber when the flow from the pump falls below a first predetermined value and for preventing the flow of fluid to said chamber when the flow from the pump falls below a second predetermined value below said first predetermined value, whereby said valve member moves rapidly to its closed position, said first valve member being slidable in a bore and defining said chamber at one end thereof, said first valve member having a venting port therein communicable with a low pressure return means, said valve means including a second valve member slidable in the first valve member and constructed to close said venting port when the flow in said supply passage exceeds -a predetermined value to cause a rapid pressure rise in said chamber preparatory to opening said first valve member and to open said venting port when the flow in said supply passage means falls below a predetermined value at pump shut-down to permit rapid closure of said first valve member.

-6. The combination as defined in claim 2 including an air purging valve in said supply passage means.

7. A fuel burner valve device for controlling the flow of fuel between a fuel pump and a burner nozzle, comprising: passage means for supplying fluid from said pump, a regulating valve including a valve chamber having a burner nozzle outlet port therein, said pass-age means being connected to supply fluid to said chamber, a valve member in said chamber movable from a closed position preventing the flow of fluid from said chamber through said burner nozzle port and an open position permitting fluid flow through said nozzle port, means biasing said valve member to its closed position, valve means between said pump and said chamber responsive to flow from said pump for venting said chamber when the flow from the pump falls below a first predetermined value and for preventing the flow of fluid to said chamber when the flow from the pump falls below a second predetermined value below said first predetermined value, whereby said valve member moves rapidly to its closed position, including a valve housing having a bore therein, said outlet port being in one end of said bore, said valve member being generally cylindrical and having a valve surface at one end thereof defining said chamber at said one end of said bore, said valve surface being cooperable with said burner nozzle outlet port to control the flow of fluid therethrough, said valve member being hollow, spring means engaging said valve member and urging it toward the closed position and for maintaining a substantially constant pressure flow through said outlet port, return passage means in said housing communicating with said bore, and land means on said valve member blocking communication between the chamber and the return passage means around the valve member in its closed position and permitting a portion of the fluid in said chamber to be bypassed through said return passage means upon a predetermined movement of said valve member from its closed position.

8. The combination as defined in claim 7, wherein said valve means includes a second hollow valve member slidable in said first valve member, a valve seat for said second valve member fixed within the end of said first valve member opposite said first member valve surface, said supply passage means including a passage in said housing communicating with said bore and an inlet port in said first valve member communicating with said passage and with the hollow interior of said first valve member adjacent said seating surface, said second valve member having an axial bore therethrough defining an orifice for conveying fluid from said inlet port to the said chamber, second spring means seated in said first valve member and urging said second valve member against the valve seat in a direction opposite said first spring means, vent port means in said first valve member in communication with said return passage means in said housing, said second valve member being flow responsive and having a portion thereof slidable over said vent port means to close the same at a first predetermined flow of fluid through said orifice, said second valve means being responsive to a reduction in flow through said orifice to open said vent port means permitting the fluid in said chamber and within said valve members to escape through the vent port means to effect rapid closure of said first valve member.

9. A fuel supply unit for an oil burner, comprising: a housing; a reservoir in said housing; a rotary pump in said housing connected to receive fluid from said reservoir; a pump outlet passage in said housing for conveying fluid under pressure from said pump; a regulating valve assembly in said housing including a valve bore having an outlet at one end thereof adapted to be connected to burner nozzles, said pump outlet passage being connected to supply fluid to said bore adjacent the center thereof, a first hollow valve member slidable in said bore having a valve surface at one end thereof adapted to engage and close said burner nozzle outlet and movable away from said seat to open said burner nozzle outlet and permit fluid to flow from said pump outlet passage through said outlet, spring means in said bore urging said first valve member closed and constructed to maintain a substantially constant fluid pressure in said burner nozzle outlet, inlet port means in said first valve member providing continuous communication between said pump supply passage and the interior of said first valve member, a seating surface fixed to and closing the other end of said first valve member and continuously communicating with said inlet port means, a second hollow valve member slidable in said first valve member and having a valve surface engageable with said valve seat to prevent fluid flow when closed from said inlet port means to said first member valve surface, an axial bore through said second valve member permitting fluid to flow from said inlet port means to said valve surface when said second valve member is open, said second valve member having opposed ditferential surfaces adjacent the orifice so that the position of the second valve member is dependent on flow through said orifice, and second spring means in said first valve member for urging said second valve member surface against said valve seat wherein said bore in the second member is closed, said second valve member being responsive to a predetermined flow in said pump supply passage for opening and permitting fluid pressure acting on said first valve member surface to open said first valve member so that fluid passes through said outlet port to the burner nozzles, and being responsive to a reduction in flow to a predetermined value in said pump supply passage for closing and cutting off the supply of fluid to said first member valve surface thereby permitting said first valve member to close said burner nozzle outlet.

10. The combination defined in claim 9 and further including return passage means in said housing for conveying fluid from said bore, land means on said first valve member spaced from said first member valve surf-ace for preventing fluid flow around said first valve member to said return passage means when the first valve member is closed, said land means permitting communication around said first valve member with said return passage means upon a predetermined movement of said first valve member from its closed position whereby a portion of the fluid flow is bypassed through said return passage means after the first valve member opens.

11. The combination defined in claim 10, and further including vent port means in said first valve member between said seating surface and said first member valve surface communicating with said return passage means, said valve member having a portion thereof closing said vent port means upon predetermined movement from its closed position and opening said vent port means at a predetermined flow through said axial bore for permitting rapid closure of said first valve member.

12. A regulating valve assembly for an oil burner fuel pump, comprising: supply passage means for conveying fluid from the pump, return passage means adapted to be connected to return fluid to the pump or a tank, first valve means including a housing having a nozzle outlet port adapted to be connected to burner nozzles, -a movable valve member slidable in said housing for controlling flow through said outlet port from said supply passage means and defining a valve chamber in said housing, said valve member also controlling flow from said supply passage means to said return passage means, a purging valve in said supply passage means for conveying the fluid and air mixture therefrom during start-up, and second valve means for blocking flow from said supply passage means to said valve chamber during p 13. A regulating valve assembly for an oil burner fuel pump, comprising: supply passage means for conveying fluid from the pump, return passage means adapted to be connected to return fluid to the pump, first valve means including a housing having a nozzle outlet port adapted to be connected to burner nozzles, a movable valve member slidable in said housing for controlling flow through said outlet port from said supply passage means and defining a valve chamber in said housing, said valve member also controlling flow from said supply passage means to said return passage means, a purging valve in said supply passage means for conveying the fluid and air mixture therefrom during start-up, second valve means for blocking flow from said supply passage means to said return passage means during purging, and said second valve means blocking flow from the supply passage means to said valve chamber during purging.

14. A regulating valve assembly for an oil burner fuel pump, comprising: supply passage means for conveying fluid from the pump, return passage means adapted to be connected to return fluid to the pump, first valve means including a housing having a nozzle outlet port adapted to be connected to burner nozzles, a movable valve member slidable in said housing for controlling flow through said outlet port from said supply passage means and defining a valve chamber in said housing, and second valve means in series with said first valve means for controlling flow of fluid from said supply passage means to said return passage means and said valve chamber, said second valve means being responsive to a predetermined flow therebetween for blocking communication between said valve chamber and said return passage means whereby pressure in said chamber will rapidly rise at said predetermined flow and said first valve means will rapidly open delivering fluid to said outlet port.

15. The combination as defined in claim 14, wherein said second valve means is responsive to a predetermined flow therethrough for providing communication between said valve chamber and said return passage means to permit rapid closure of said first valve means on shut down.

16. The combination as defined in claim 15, wherein said second valve means includes a differential valve member slidable in said first valve member.

17. A fuel burner valve device for controlling the flow of fuel between a fuel pump and a burner nozzle, comprising: passage means for supplying fluid from said pump, a regulating valve including a valve chamber having a burner nozzle outlet port therein, said passage means being connected to supply fluid to said chamber, a valve member in said flow of fluid from said chamber through said burner nozzle port and an open position permitting fluid flow through said nozzle port, means biasing said valve member to its closed position, and separate valve means in series between said pump and said chamber responsive to fluid in said passage means for venting said chamber when a parameter of the fluid from said passage means fall below a predetermined value.

18. A fuel burner valve device for controlling the flow of fuel between a fuel pump and a burner nozzle, comprising: passage means for supplying fluid from said pump, a regulating valve including a valve chamber having a burner nozzle outlet port therein, said passage means being connected to supply fluid to said chamber, a valve member in said chamber movable from a closed position preventing the flow of fluid from said chamber through said burner nozzle port and an open position permitting fluid flow through said nozzle port, means biasing said valve member to its closed position, and separate valve means having an orifice in series between said pump and said chamber responsive to fluid in said passage means for venting said chamber when a parameter of the fluid from said passage means falls below a predetermined value.

References Cited UNITED STATES PATENTS 3,312,177 4/ 1967 Eckerle. 2,749,935 6/1956 Heard 137-108 2,763,336 9/1956 Erikson 137l08 3,011,506 12/ 1961 Schwartz.

WILLIAM F. ODEA, Primary Examiner. W. H. WRIGHT, Assistant Examiner.

US. Cl. X.R. 103-41, 42; 1371l5, 117 

